Sunday's horse death was the third horse death at the park since Dec. 26 for Hall of Fame trainer Jerry Hollendorfer, the Times said.

People for the Ethical Treatment of Animals (PETA) released a statement on the latest horse death via the organization's senior vice president, Kathy Guillermo:

"Santa Anita and all California tracks must suspend racing until the ongoing investigation by the district attorney is complete and the new rules have been strengthened. Decreasing the number of broken bones is not enough. PETA and Social Compassion in Legislation are currently working with The Stronach Group and the California Horse Racing Board to enact new regulations and laws to stop all deaths. Nothing short of a zero-fatality rate is acceptable."

Santa Anita was closed for racing for most of March as authorities studied the racing surface and investigated whether heavy rains in Southern California had contributed to the rise in deaths at the track, but no problems were found.

Races resumed after the state horse racing board approved a series of safety measures, including limits on certain types of medications administered to horses.

In early April, Santa Anita officials announced a series of new measures to help bolster the safety of horses at the track, including restrictions on certain medications, requiring trainers to get permission in advance before putting a horse through a workout and investing in diagnostic equipment to aid in the early detection of pre-existing conditions.